During the drilling, extraction, and production of petroleum materials, extreme conditions can be experienced downhole that make these activities difficult. For example, some wells can have high salinity, extreme pH, high temperature, high pressure conditions. Wells with undisturbed bottomhole temperatures above about 150-177° C. can be classified as high temperature, with temperatures above about 204-218° C. ultra-high temperature, and with temperatures above about 260° C. generally considered extreme-high temperature. Wells with wellhead pressure greater than about 10,000-15,000 psi are considered high pressure, with pressures above about 15,000-20,000 psi ultra-high pressure, and with pressures above about 30,000 psi generally considered extreme high pressure.
During the drilling, completion, and production phases of wells for petroleum or water extraction, the downhole use of compositions having high viscosities is important for a wide variety of purposes. Higher viscosity fluids can more effectively carry materials to a desired location downhole, such as proppants. Similarly, higher viscosity drilling fluids can more effectively carry materials away from a drilling location downhole.
Various materials used to affect properties of fluids downhole can degrade and become ineffective under the extreme conditions experienced downhole in some wells. For example, guar gum can be used to increase viscosity but can degrade under various extreme downhole conditions.